Context

1. Climate model simulations of clouds are improving Stephen. Klein, Yuying Zhang, Mark Zelinka, Robert Pincus, Jim Boyle and Peter Gleckler Context Metrics demonstrate improvement particularly for cloud reflectivity, less so for cloud amount • With new simulations (CFMIP2/CMIP5, ~ 2012) we can test if clouds in the world’s climate models are improved in comparison to older simulations (CFMIP1/CMIP3, ~2004). Approach We compare simulations of the climatological amount, reflectively, and altitude of clouds to data from the International Satellite Cloud Climatology Project (ISCCP). An ISCCP simulator is applied to the clouds of 19 climate models. Arrows pointed to the left demonstrate that the newer models are better Conclusions Newer models from each modeling center have reduced amounts of highly reflective cloud in better agreement with satellite observations • Clouds simulations in climate models are improving – a necessary but insufficient step towards increasing our confidence in their predictions • Climate models have reduced the reflectivity of their clouds ameliorating the “too few – too bright” problem where the time-mean radiation balance is well-simulated by having the compensating errors of too few clouds which are too reflective Satellite Observations Publication Klein, S. A., Y. Zhang, M. D. Zelinka, R. Pincus, J. Boyle, and P. J. Gleckler (2013), Are climate model simulations of clouds improving? An evaluation using the ISCCP simulator. J. Geophys. Res., 118, 1-14. doi:10.1002/jgrd.50141, 2013